1. Field of the Invention
The present invention relates generally to surgical instruments. More particularly, the present invention relates to cannulae and sleeves used to irrigate and evacuate body cavities during endoscopic or minimally invasive surgery.
2. Background Information
Endoscopic surgical procedures (sometimes referred to as "laparoscopy") are becoming increasingly accepted in the medical community for many surgical procedures. In endoscopic surgery, a small incision typically is made in the abdominal wall through which a fiber-optic viewing device ("endoscope")is inserted into the abdominal or other body cavity. Other small incisions are made through which surgical instruments are passed to dissect tissue and perform other operations. Frequently, the body cavity is insufflated with an inert gas, such as CO.sub.2, which provides space in which to manipulate surgical instruments and to view the area in which surgical operations are to take place. Endoscopic procedures are preferable to many conventional surgical techniques because they are less invasive and therefore permit patients to recover more quickly and reduce the rate of infection.
Because the endoscopic surgical site is enclosed within the body cavity, irrigation and evacuation of the site is rendered somewhat more difficult in endoscopic procedures than in open or conventional techniques. In both open and endoscopic surgical procedures, suction and irrigation tubes are placed in the surgical site, one to evacuate fluids and one to irrigate with fluid. Provision of two separate tubes for irrigation and evacuation is cumbersome. Commonly owned U. S. Pat. No. 4,668,215, May 26, 1987 to Allgood, discloses a valving arrangement whereby irrigation and evacuation can be accomplished with a single line or tube passed through an endoscopic cannula or sleeve. Similarly, commonly owned U.S. Pat. No. 4,776,840, Oct. 11, 1988 to Freitas et al. discloses a device for simultaneously providing irrigation and evacuation that is adapted for single-handed use. Nevertheless, a tube passes from the device, through a cannula or sleeve, and into the surgical site.
Irrigation and evacuation tubes have been combined into endoscopic cannulae or sleeves to combine previously separate apparatus into one. This cannula is passed through an incision and provides a tube through which suction may be applied to evacuate blood and other fluids from the surgical site and through which fluid may be provided to irrigate the surgical site.
To permit the surgical instrument to pass unobstructed through the irrigation and evacuation cannula or sleeve, complex valving arrangements are required to permit connection of evacuation and irrigation apparatus with the cannula. These arrangements commonly take the form of trumpet valves, which are arranged at generally right angles to the lumen or passage extending through the cannula or sleeve. Thus, during irrigation and evacuation, fluids and bits of tissue travel through a convoluted path between the irrigation and evacuation conduits, the valves, the cannula passage, and into and out of the body cavity. Examples of such prior-art cannula can be found in commonly assigned U.S. Pat. No. 5,312,373, May 17, 1994 to Freitas, and in U.S. Pat. No. 4,696,305 to Von Berg. Such prior-art cannulae are difficult to clean and sterilize, and thus to reuse. Additionally, the convoluted fluid path has generally poor fluid dynamics and makes the apparatus prone to clogging.
A need exists, therefore, for surgical irrigation and evacuation cannulae having improved valving arrangements that permit fluid to flow through the cannula in a more linear fashion and that are thus more easily cleaned and sterilized and less prone to clogging.